Movement of ions across cellular membranes is carried out by specialized proteins. TRP channels are one large family of non-selective cation channels that function to help regulate ion flux and membrane potential. TRP channels are subdivided into 6 sub-families including the TRPV family. TRPV3 is a member of the TRPV class of TRP channels.
TRPV3 is a calcium permeable channel, specifically a calcium permeable nonselective cation channel. In addition to calcium ions, TRPV3 channels are permeable to other cations, for example sodium. Thus, TRPV3 channels modulate membrane potential by modulating the flux of cations such as calcium and sodium ions. TRPV3 receptors are mechanistically distinct from voltage-gated calcium channels. Generally, voltage-gated calcium channels respond to membrane depolarization and open to permit an influx of calcium from the extracellular medium that result in an increase in intracellular calcium levels or concentrations. In contrast, TRP channels which are non-selective cation channels are generally ligand gated (such as 2-aminoethoxydiphenyl borate [2-APB], heat, and vanilloids), long lasting, and produce more prolonged changes in ion concentration. These mechanistic differences are accompanied by structural differences among voltage-gated and TRP channels. Thus, although many diverse channels act to regulate ion flux and membrane potential in various cell types and in response to numerous stimuli, it is important to recognize the significant structural, functional, and mechanistic differences among different classes of ion channels.
TRPV3 proteins are thermosensitive channels expressed in skin cells (Peier et al. Science (2002), 296, 2046-2049) and dorsal root ganglion, trigeminal ganglion, spinal cord and brain (Xu et al. Nature (2002), 418, 181-185; Smith et al. Nature (2002), 418, 186-188). TRPV3 is also highly expressed in skin. In a keratinocyte cell line, stimulation of TRPV3 leads to release of inflammatory mediators including interleukin-1. Thus TRPV3 may also play an important role in regulating inflammation and pain that results from the release of inflammatory stimuli. Particular TRPV3 proteins that may be used in screening assays, as described herein, to identity compounds that modulate a function of TRPV3 include, but are not limited to human TRPV3, mouse TRPV3, rat TRPV3 and Drosophila TRPV3. US 2004/0009537 (the '537 application) disclosed sequences corresponding to human, mouse, and Drosophila TRPV3. For example, SEQ ID Nos 106 and 107 of the '537 application correspond to the human nucleic acid and amino acid sequences, respectively. SEQ ID Nos 108 and 109 of the '537 application correspond to the mouse nucleic acid and amino acid sequences, respectively.
TRPV3 function has been basically implicated in the reception and transduction of pain. Accordingly, it would be desirable to identify and make compounds that can modulate one or more functions of TRPV3.
WO 2007/056124 and WO 2006/017995 discloses TRPV3 modulators, in particular antagonists, for treatment of various diseases mediated TRPV3.
WO 2006/065686 and WO 2007/042906 disclose benzopyran derivatives.
In efforts to discover better analgesics, there still exists a need for therapeutic treatment of diseases, conditions and/or disorders modulated by TRPV3.